1. Field of the Invention
The present invention relates to spark plug cleaners designed for workshop use for amateur internal combustion engine maintenance.
2. Description of the Prior Art
A number of different types of internal combustion engine spark plug cleaners are commercially available for use by amateur mechanics. Some commercially available embodiments are designed for a plurality of spark plugs, while others accomodate but a single plug at a time. Virtually all conventional embodiments of such spark plug cleaners employ an impeller which rotates at a high speed and sucks grit axially toward the impeller near its center and flings the grit outwardly toward a spark plug socket or a plurality of sockets.
The spark plug sockets in conventional plug cleaners may be either horizontally disposed, vertically disposed, or disposed at an angle between the horizontal and vertical. In those spark plug cleaners in which the plug sockets are mounted horizontally, the impeller rotates about a vertically disposed shaft. In such conventional devices, there has been a consistent problem in recycling the grit to the impeller for reuse. Once the grit has inpinged upon the spark plug electrode to effectuate cleaning, its momentum is quickly spent and it falls to the floor of the confining container.
The principal difficulty in conventional systems arises in returning the spent grit to the impeller for reuse. In conventional devices with impellers mounted about vertical axes a suction is created to draw the grit upwardly for this purpose. However, in conventional devices it has been extremely difficult to recycle grit to any significant degree because of the low suction that is normally produced by the motors and impellers utilized. In one commercially available device, a helical or spiral ramp is defined about a vertical axis coaxial with the impeller axis. The spiral about the vertical axis is intended to slope siginficantly to allow the grit to reach the impeller quickly. Nevertheless, the vertical spiral configuration necessarily forces the grit against the outer cylindrical confines of the spiral channel and as a consequence, the grit arrives at the impeller intake at a relatively low velocity. The rotation of the impeller imparts additional velocity to the grit to increase its momentum to impinge upon the spark plug electrodes. However, since the grit has very little momentum entering the impeller, its momentum as it strikes the spark plug electrodes is developed almost entirely within the impeller.
Other spark plug cleaners have sought to enhance suction by providing relatively narrow cylindrical tubes leading from the impeller inlet to the collection floor of the plug cleaning chamber. In this fashion, suction is applied over a smaller cross sectional area, and hence a greater vacuum is produced. However, because suction is applied over a small area there is a tendency for the grit at the collection floor in the immediate vicinity of the suction tube to be quickly depleted, and hence the density of grit passed through the impeller is reduced.